It took a few hours cleaning the sanded surfaces from grease and dust. Finally I positioned them in the painting booth this way so I can reach all sides without accidentally walking into a piece that I just painted. The painting of all hard top parts and doors used 2 liters of epoxy primer.
The final result turned out very well. A nice thick coat ready to be sanded with 500 grit sandpaper for its final layer.
See pics for the process.